The energy services company that Dick Cheney served for much of the last five years as chairman and chief executive has agreed to let Mr. Cheney, the Republican vice-presidential candidate, retire with a package worth an estimated $20 million, according to people who have reviewed the deal.

The board of the Halliburton Company, which is based in Dallas, approved the arrangements on July 20, five days before Gov. George W. Bush announced his selection of Mr. Cheney as his running mate.

The board's vote allowed Mr. Cheney to avoid a potentially costly aspect of his employment contract, which said he would forfeit some of his compensation if he retired before age 62 without the board's permission. This provision, known as golden handcuffs, is routinely included in executives' contracts to give them incentives to stay.

Mr. Cheney, who spent much of his life as a public official and federal employee, became a wealthy man in his years with Halliburton. He has been paid at least $12.5 million by Halliburton since he joined the company in 1995 and has received stock and options worth nearly $39 million at its current share price.

By permitting Mr. Cheney, who is 59, to treat his departure as early retirement, the directors allowed him to keep $10 million worth of stock and options he would have forfeited had he simply resigned, the company's public filings show. It was not clear whether the $10 million was part of the retirement package or in addition to it.

One of those briefed on the plan said that the board was told the package totaled about $20 million.

While not extraordinarily large by current corporate standards, Mr. Cheney's retirement package solidifies and expands his personal stake in the oil industry in general, and Halliburton in particular, while he is on the campaign trail confronting energy policy issues that will affect Halliburton's performance.

Dirk Vande Beek, Mr. Cheney's campaign spokesman, and a spokeswoman for Halliburton both refused yesterday to confirm any details about the retirement arrangement. Mr. Vande Beek said details were being worked out. Mr. Cheney, he said, will remain an employee of Halliburton until Aug. 16 with the title ''chairman in transition.''

The price of Halliburton stock is substantially higher than it was when Mr. Cheney took over but his tenure was not an unqualified success. The Halliburton board annually sets financial goals for the company with the understanding that executive bonuses will be withheld if the targets are not met. The company failed to meet those targets in both 1998 and 1999, although the board decided to pay Mr. Cheney and other executives bonuses anyway in 1998 because they had engineered a major merger with Dresser Industries, another oil services company. That bonus came to $1.15 million for Mr. Cheney, nearly as much as his $1.18 million salary for the year. In 1999, however, the bonus was withheld.

Mr. Cheney has said in interviews that he will sell off his Halliburton stock if the Republican ticket prevails in the fall. It is not yet clear how Mr. Cheney might handle his stock options, a major part of his wealth, which if retained would give him a stake in the company's performance for years to come.

The options give him the right to buy shares at a set price for up to 10 years. Some of Mr. Cheney's options, however, cannot be exercised before January, unless the board waives restrictions on them. Other options give Mr. Cheney the chance to buy Halliburton stock at more than its current market price of $51 a share, worthless today but potentially valuable if he can hold them until the company's stock rises.

A spokesman for the company, Wendy Hall, declined to discuss Mr. Cheney's retirement. Ms. Hall said that the company allowed some executives to retire with full benefits after age 55 and that details of Mr. Cheney's arrangement would be made public next week.

According to one board member, the package approved for Mr. Cheney was not discounted to reflect either his age or his short tenure.

''Whatever the contract calls for'' is what was approved for Mr. Cheney, said W. R. Howell, a Halliburton director and former chairman and chief executive of the J. C. Penney Company. ''He's entitled to full retirement.''

Mr. Howell added, ''There was nothing done at the board level of an exceptional nature for Dick Cheney. The press release indicated that Dick Cheney is retiring and that's what he's doing.''

According to reports filed with the Securities and Exchange Commission, Mr. Cheney is covered by two retirement plans at Halliburton, a profit-sharing plan and a second plan, intended to provide a minimum pension if the profit-sharing funds are inadequate. The company has not disclosed how much Mr. Cheney stands to receive from those plans.

Halliburton's financial statements do not describe its early retirement program, but such arrangements typically involve a substantial reduction in the pension benefits the employee receives.

In recent years, a number of corporate boards have granted departing chief executives pension benefits for which they did not qualify under strict terms of their contracts.

Mr. Cheney joined the company's board on Aug. 10, 1995, and became chief executive on Oct. 1, 1995. While details of the retirement plans affecting Mr. Cheney are not clear from the company's public filings, many such plans require an employee to have at least five years of service to receive any benefits, a milestone Mr. Cheney did not pass until Aug. 10 at the earliest, assuming his board service is counted.

Under his leadership, the company has won two important international contracts, one with Petroleos Brasileiros, or Petrobras, the Brazilian oil giant, the other a Defense Department contract for the reconstruction of war-damaged Kosovo.

Also on Mr. Cheney's watch, to save money, Halliburton laid off thousands of employees and reduced retirees' medical benefits.

Mr. Cheney's decision not to sell his stock until after the election drew some criticism.

''It is a built-in conflict of interest throughout the campaign,'' said Chuck Lewis of the Center for Public Integrity in Washington.

Ari Fleischer, a spokesman for the Bush campaign, rejected that view. ''America is best served when good people from the private sector are willing to return to the public sector,'' Mr. Fleischer said.

''There are many good people like former Treasury Secretary Robert Rubin who have done so,'' he added. ''Surely we want to encourage their return.''

The Halliburton board was well within its legal powers in granting Mr. Cheney full retirement benefits before the date in his contract, said John C. Coffee Jr., a securities law professor at Columbia Law School.

''The purpose of such golden handcuffs is to keep an attractive executive from taking a competitive job in business,'' Professor Coffee said, adding, ''I don't think you need to extend that concept to keep someone from becoming pope, vice president or chief justice.''

The decision is certainly a significant one for Mr. Cheney's own financial security, since his tenure at Halliburton came after he had spent most of his career in government service as a congressman from Wyoming and as secretary of defense -- without amassing significant wealth.

Now, however, he is wealthy. He exercised options on 100,000 shares and sold the stock at the end of May, earning a profit of $3 million. The other options and restricted stock he was given are worth $35.7 million at current prices.

History offers few examples of how other candidates in Mr. Cheney's circumstances handled the effect of a campaign on their personal financial interests.

Most candidates on a presidential ticket, even those with business experience, entered the race from state or local political office, said Judge Leslie H. Southwick, author of the book ''Presidential Also-Rans and Running Mates, 1788-1980.'' It is far less common for a full-time corporate manager to step directly from the executive suite onto the campaign trail, where campaign issues can affect his personal fortune.

There have been exceptions, of course. For example, Wendell Willkie was president of Commonwealth and Southern, a large utility holding company, when he made his bid for the presidency as a Republican in 1940 at a time when utilities were vehemently opposing New Deal projects like the Tennessee Valley Authority, Judge Southwick noted.

In 1992, H. Ross Perot sought the presidency on the Reform Party ticket while overseeing Perot Systems, a computer systems company. But the company was not publicly traded then.

Jimmy Carter, who had already served as governor of Georgia, campaigned for the White House in 1976 while helping run his family's struggling peanut business.